I have a Windows 10 machine with i7 4790k and 16 Gigs of ram with a 6400 rpm HDD. I primarily use Ableton. The machine is 3 years old now and it has become considerably slower. The sessions take more time to load and it takes more CPU usage than it used to. In short it doesn't read the samples at the speed it used to when it was new. Now should I upgrade my RAM, processor or Hard drive is my question.

Those specs are better than mine and my laptop runs smooth and quickly.

I'm wondering, if your machine is so slow, you might benefit from cleaning it (CCleaner), or even reinstalling the OS and rebuilding from scratch. This is what I did when I had an issue with my laptop a few months ago. Since that reinstall of the OS, my laptop now runs three or four times quicker, and I also benefitted from taking the opportunity to only install what I really need with no fluff to clutter it up all over again.

I use CCleaner (it's free!) about once a week and it's sibling Defragger about once every three months...

I find Windows Defender is perfectly adequate (98%) of the time to keep things safe, but if I have suspicions I also use Malwarebytes.

On the subject of CCleaner, it's worth exploring it's other features like cleaning the Registry and checking/clearing what apps are starting on start-up. Also deleting unused software won't come amiss, although it's probably not making any significant difference.

I'm wondering, if your machine is so slow, you might benefit from cleaning it (CCleaner), or even reinstalling the OS and rebuilding from scratch. This is what I did when I had an issue with my laptop a few months ago. Since that reinstall of the OS, my laptop now runs three or four times quicker, and I also benefitted from taking the opportunity to only install what I really need with no fluff to clutter it up all over again.

Thanks ! I do have CCleaner, but I guess I'll try reinstalling the OS also.

I use CCleaner (it's free!) about once a week and it's sibling Defragger about once every three months...

I find Windows Defender is perfectly adequate (98%) of the time to keep things safe, but if I have suspicions I also use Malwarebytes.

On the subject of CCleaner, it's worth exploring it's other features like cleaning the Registry and checking/clearing what apps are starting on start-up. Also deleting unused software won't come amiss, although it's probably not making any significant difference.

A 2TB 7,200 rpm drive in a USB 3.0 caddy will not set you back that much and I am pretty sure you could run your samples from that?

Then, such a drive will be invaluable if you do decide to do an OS re-install. You can make a backup image of the internal drive. I used the free Macrium Reflect imaging software, others here might have other suggestions? Once you have the drive safely stashed (in a separate partition perhaps?) you can clean up with the confidence that you will not lose anything.